1. Field of the Invention
The present invention relates to a medical device and, more specifically, to an ultrasound device.
2. Prior Art
With the advent of laparoscopic surgery, ultrasound imaging can be used to image beneath the surface of organs. Implementation is achieved by the introduction of an ultrasound imaging probe through a cannula. FIG. 1A shows the end of one such probe 10 with a distal transducer array 12 on the end of its shaft 14. The array 12 is positioned at tissue 16 to be imaged. Images are generated by the transducer array located at the end of a shaft, and are transmitted via a signal cable through the shaft and handle. Images are reconstructed by computer connect by cable to the probe handle and displayed on a CRT screen. A typical ultrasound image 15 corresponding to FIG. 1A is shown in FIG. 1B. It is desirable to have a flexible tip to the shaft such that the transducer array can be bent relative to the axis of the shaft. A skilled surgeon can maneuver the probe tip to the organ/area of interest.
In conjunction with ultrasound imaging, there is also a need to obtain biopsy samples of suspicious areas. The use of ultrasound allows the surgeon to guide the biopsy procedure. This procedure, generically called ultrasound guided biopsy is depicted in FIG. 2A. The surgeon positions the probe 10 and, using the ultrasound image 15 shown in FIG. 2B that is viewed on a display, guides the biopsy needle 18 to the suspect area B. The advantage of this method is the accuracy by which a laparoscopic surgeon can obtain biopsy samples.
In laparoscopic surgery, as illustrated in FIG. 2A, both probes and needle are introduced via separate cannulas. The workload on the surgeon to execute a biopsy is high as he must coordinate the location of two objects (probe and needle) while looking at a real time ultrasound image and a video image. U.S. Pat. No. 5,437,283 describes a laparascopic ultrasound probe with integrated biopsy capabilities. The probe can function as an image only probe and, with an attachment, as a biopsy probe. FIG. 3A schematically shows the ultrasound probe 20 and biopsy device 22 of U.S. Pat. No. 5,437,283. The biopsy device 22 generally comprises a needle 24, a guide 25 and a gun 27. By virtue of the attachment, the biopsy needle 24, made of conventional stainless steel, is constrained to follow a sampling trajectory that always passes within of the ultrasound image (See FIG. 3C). This approach greatly reduces the workload of the physician performing laparoscopic ultrasound guided biopsy.
The use of laparoscopic ultrasound probes with deflectable tips exposes the shortcomings of U.S. Pat. No. 5,437,283. Probes with the attachment 22 will need a larger cannula in the patient. The biopsy needle 24 is constrained to be parallel with the rigid shaft 26. Deflectable tips 28 can only be two-way deflectable (not four-way deflectable) because deflection on the perpendicular lateral direction from that illustrated in FIG. 2A will cause the image to be out of the trajectory plane of the biopsy needle. It is obvious that the bending neck 30 can only deflect in one direction, away from the path of the needle 24, otherwise the tip 28 would block the path of the needle. Because the tip 28 can only be deflected away from the path of the needle 24 in one direction, this limits the flexibility of the probe. Another problem is that, at the extremes of deflection, the image of the trajectory is small. Furthermore, it is not possible to preprogram the trajectory of the needle's path because the angle which the biopsy needle enters the ultrasound image will be a function of the deflection angle of the neck 30 and tip 28. Thus the target line for the biopsy needle cannot be determined in advance. It can only be estimated from the deflection angle.